Distributed data centers and local storage/computing

Users increasingly store data collections such as digital photographs on multiple personal devices, each of which typically offers a storagemanagement interface oblivious to the contents of the user’s other devices. As a result, collections become disorganized and drift out of sync. This paper presents Eyo, a novel personal storage system that provides device transparency: a user can think in terms of “file X”, rather than “file X on device Y ”, and will see the same set of files on all personal devices. Eyo allows a user to view and manage the entire collection of objects from any of their devices, even from disconnected devices and devices with too little storage to hold all the object content. Eyo synchronizes these collections across any network topology, including direct peer-to-peer links. Eyo provides applications with a storage API with first-class access to object version history in order to resolve update conflicts automatically. Experiments with several applications using Eyo— media players, a photo editor, a podcast manager, and an email interface—show that device transparency requires only minor application changes, and matches the storage and bandwidth capabilities of typical portable devices. Read More ›

Despite increasing usage of mobile computing, exploiting its full potential is difficult due to its inherent problems such as resource scarcity, frequent disconnections, and mobility. Mobile cloud computing can address these problems by executing mobile applications on resource providers external to the mobile device. In this paper, we provide an extensive survey of mobile cloud computing research, while highlighting the specific concerns in mobile cloud computing. We present a taxonomy based on the key issues in this area, and discuss the different approaches taken to tackle these issues. We conclude the paper with a critical analysis of challenges that have not yet been fully met, and highlight directions for future work. Read More ›

The convergence of mobile computing and cloud computing is predicated on a reliable, high-bandwidth, end-to-end network, which is difficult to guarantee in hostile environments. However, virtual-machine-based cloudlets located in close proximity to associated mobile devices can overcome this deep-rooted problem. Read More ›

Mobile applications are becoming increasingly datacentric – often relying on cloud services to store, share, and analyze data. App developers have to frequently manage the local storage on the device (e.g., SQLite databases, file systems), as well as data synchronization with cloud services. Developers have to address common issues such as data packaging, handling network failures, supporting disconnected operations, propagating changes, and detecting and resolving conflicts. To free mobile developers from this burden, we are building Simba, a platform to rapidly develop and deploy datacentric mobile apps. Simba provides a unified storage and synchronization API for both structured data and unstructured objects. Apps can specify a data model spanning tables and objects, and atomically sync such data with the cloud without worrying about network disruptions. Simba is also frugal in consuming network resources. Read More ›

The availability of real-time continuous speech recognition on mobile and embedded devices has opened up a wide range of research opportunities in human-computer interactive applications. Unfortunately, most of the work in this area to date has been confined to proprietary software, or has focused on limited domains with constrained grammars. In this paper, we present a preliminary case study on the porting and optimization of CMU Sphinx-11, a popular open source large vocabulary continuous speech recognition (LVCSR) system, to hand-held devices. The resulting system operates in an average 0.87 times real-time on a 206 MHz device, 8.03 times faster than the baseline system. To our knowledge, this is the first hand-held LVCSR system available under an open-source license Read More ›

Mobile computing continuously evolve through the sustained effort of many researchers. It seamlessly augments users' cognitive abilities via compute-intensive capabilities such as speech recognition, natural language processing, etc. By thus empowering mobile users, we could transform many areas of human activity. This article discusses the technical obstacles to these transformations and proposes a new architecture for overcoming them. In this architecture, a mobile user exploits virtual machine (VM) technology to rapidly instantiate customized service software on a nearby cloudlet and then uses that service over a wireless LAN; the mobile device typically functions as a thin client with respect to the service. A cloudlet is a trusted, resource-rich computer or cluster of computers that's well-connected to the Internet and available for use by nearby mobile devices. Our strategy of leveraging transiently customized proximate infrastructure as a mobile device moves with its user through the physical world is called cloudlet-based, resource-rich, mobile computing. Crisp interactive response, which is essential for seamless augmentation of human cognition, is easily achieved in this architecture because of the cloudlet's physical proximity and one-hop network latency. Using a cloudlet also simplifies the challenge of meeting the peak bandwidth demand of multiple users interactively generating and receiving media such as high-definition video and high-resolution images. Rapid customization of infrastructure for diverse applications emerges as a critical requirement, and our results from a proof-of-concept prototype suggest that VM technology can indeed help meet this requirement. Read More ›

Increasingly people manage and share information across a wide variety of computing devices from cell phones to Internet services. Selective replication of content is essential because devices, especially portable ones, have limited resources for storage and communication. Cimbiosys is a novel replication platform that permits each device to define its own content-based filtering criteria and to share updates directly with other devices. In the face of fluid network connectivity, redefinable content filters, and changing content, Cimbiosys ensures two properties not achieved by previous systems. First, every device eventually stores exactly those items whose latest version matches its filter. Second, every device represents its replication-specific metadata in a compact form, with state proportional to the number of devices rather than the number of items. Such compact representation results in low data synchronization overhead, which permits ad hoc replication between newly encountered devices and frequent replication between established partners, even over low bandwidth wireless networks. Read More ›